This invention relates to a fuel injection type engine and more particularly to an improved air/fuel injector for an internal combustion engine.
One type of fuel injector which is advantageous in connection with two cycle internal combustion engine is an injector of the air/fuel type. With this type of injector, in addition to fuel, pressurized air is injected into the combustion chamber of the engine when the injector valve is opened. Although this type of device has particular advantages, there are some disadvantages with the previously proposed injectors of this type. For example, one type of injector has the fuel delivered to the injector in the area where the injector valve opens and closes. The air flow across the injector outlet when the injector valve is opened creates a vacuum which assist in the delivery of fuel. However, the amount of vacuum produced will vary in relation to the lift of the valve and also during the opening and closing of the valve when the opening area varies. As a result, the fuel delivery to the engine can become unstable and erratic. In addition, it is often desirable to change the amount of lift of the valve during engine running to accommodate changes in engine performance. Of course, the variable lift will give further rise to differences in the amount of fuel injected.
These problems can be avoided to some extent if the fuel is injected in an area other than the area of the injection valve and its seat. However, when this is done the fuel must be injected into a high pressure area and hence the fuel pressure must be greater than the air pressure. This gives rise to the cost of higher pressure fuel injectors and also increases the likelihood of leakage in the system due to the higher pressure of fuel.
It is, therefore, a principal object of this invention to provide an improved air/fuel injector for an internal combustion engine.
It is a further object to this invention to provide an air/fuel injector wherein the fuel can be injected into a low pressure area and wherein the amount of fuel delivered will be independent of the operation of the injection valve.
It is a further object to this invention to provide an improved fuel/air injector of the type having an injection valve and wherein the fuel is delivered to a low pressure area upstream of the injection valve to avoid variations in the amount of fuel delivery and response to the position of the injection valve.
It is a further object to this invention to provide an improved air/fuel injector of a type wherein the fuel can be injected into a low pressure area even though high pressure air is employed to assist in the fuel delivery.